The "Fintail" (German: Heckflosse ) was a series of luxury cars produced by Mercedes-Benz from the late 1950s to the mid-1960s under the W111 chassis code. Though never officially designated as such (they were designated Peilstege, marking the end of the car in rear view mirror), the cars gained the nickname because of the distinctive rear-end which incorporates small tailfins, thought to be an understated attempt to appeal to the United States market at the time (with their outrageously finned cars, such as the Cadillacs and Buicks of the times).

The Fintail is considered part of the lineage of the Mercedes-Benz S-Class flagship model, particularly the initial 6-cylinder W111 and more luxurious W112 models. A 4-cylinder version, the W110, was introduced in 1962. In the S-Class lineage, the Fintail models were succeeded by the larger W108/W109 lines.

The Fintail models were pioneers of the automotive safety feature of crumple zones, which absorb the energies of a collision. The idea for crumple zones came from Bela Barenyi who worked as an engineer for Mercedes-Benz.

The fintail models consisted of three basic platforms:

W111 - Standard 6-cylinder luxury cars, introduced in 1959

W112- Ultra-luxurious variants with air suspension, introduced in 1961

W110 - Cheaper, 4-cylinder models with a shortened hood, introduced in 1962; "Kleinflosse" in German

As is standard practice for most automobile manufacturers, several different engine combinations and interior trim options were applied to the basic platforms, to create many different models.